This invention relates to a ultrasonic flaw detector driving apparatus for a pressure container, pipings, etc. of an atomic power plant. More specifically, the present invention relates to a mounting-dismounting mechanism of a remote-controlled, automatic ultrasonic flaw detector driving apparatus.
Regulations require the periodic inspection of a pressure container and a piping arrangement of an atomic power plant and also a nozzle portion as the joint portion of these members. For example, in the United States of America, the contents of this inspection is stipulated in detail in ASME (THE AMERICAL SOCIETY OF MECHANICAL ENGINEERS) CODE.
The inspection is generally carried out by fitting a guide rail around an object for inspection such as the pressure container or the piping and mounting a ultrasonic flaw detector driving apparatus having a ultrasonic wave probe onto the guide rail and causing it to travel thereon. Since the inspection procedure consists principally of the manual work, there are problems such as exposure of an inspector to the radioactive rays and difference in the collected data depending upon inspectors. Hence, there is a pressing need for a reliable remote-control ultrasonic flaw detector driving apparatus. However, there are strict conditions imposed on a ultrasonic flaw detector driving apparatus to be installed on the site of the inspection with regard to the functional requirements such as, scanning accuracy, weight, size, mounting-dismounting time as well as the performance aspects such as flaw detection accuracy. To this date, no apparatus has been developed which perfectly satisfies all these requirements.
As to the problem of the weight of the driving apparatus, for example, the ultrasonic flaw detector driving apparatus must be light enough for the inspector to carry it around to and from necessary positions of the object for inspection because he has sometimes to climb up and down a ladder or to pass through a narrow and limited foothold between pipings while taking the driving apparatus with him. Moreover, the fitting height and length of the driving apparatus are limited depending upon the structure of the pipings around it when the former is mounted to the latter. Though this limitation is not determined primarily, it is preferred to reduce the size of the driving apparatus to widen the range of its application. In order to minimize the exposure of the inspector to the radioactive rays, it is also necessary to reduce the time required for fitting the driving apparatus to the guide rail as short as possible. For these reasons, it is desired to obtain such a mounting-dismounting mechanism of one-touch system that is capable of shortening the time required for mounting and dismounting the ultrasonic flaw detector driving apparatus.
Further, since the site of the inspection work is of a multi-storied construction, any dropping of tools, would lead to a great danger. Hence, no tool is preferably used for mounting and dismounting the driving apparatus. In addition, the driving apparatus must be able to scan the probe up to a desired position of the object for inspection with a high level of accuracy and must have such versatility so as to be adapted to pipings of a varying diameter by simply replacing the guide rail.